MM quadruple bonds supported by cyanoacrylate ligands. Extending photon harvesting into the near infrared and studies of the MLCT statesElectronic supplementary information (ESI) available: Table S1, Fig. S1-S6. CCDC 919555 and 919556. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c3sc50322d

The compounds trans -M 2 (T i PB) 2 ( L ) 2 and trans -M 2 (T i PB) 2 ( L′ ) 2 have been prepared from the reactions between M 2 (T i PB) 4 (T i PB = 2,4,6-triisopropylbenzoate, M = Mo or W) and LH or L′H (∼2 equiv.), respectively, where L = O 2 CC(CN)&z.dbd;CH-C 6 H 4 -NPh 2 and L′ = O 2 CC(CN)&z.dbd;CH-C 4 H 3 S-C 6 H 4 -NPh 2 . These cyanoacrylate ligands promote intense M 2 δ to L or L′ π*-transitions that span the range 550-1100 nm. The two molybdenum complexes have been characterized by single crystal X-ray studies that reveal the extensive L-M 2 -L or L′-M 2 -L′ M 2 δ-ligand π-conjugation. The new compounds have been characterized by electronic structure calculations employing density functional theory (DFT) and time-dependent-DFT, cyclic voltammetry, electronic absorption and steady state emission spectroscopy and femtosecond (fs) and nanosecond (ns) time resolved transient absorption (TA) and fs time-resolved infrared spectroscopy (TRIR). The latter allows the determination of the S 1 states as 1 MLCT that are delocalized over both L and L′ . For molybdenum the T 1 states are 3 MoMoδδ* whereas for tungsten they are 3 MLCT. The incorporation of MM quadruple bonds into triphenylamine-cyanoacrylate ligands promotes intense M 2 δ to ligand π*-transitions that span the range 550-1100 nm.